The present invention relates to vehicle brake control systems, and in particular to brake system devices with greater availability and/or functionality.
The invention is based on a vehicle device having a signal input device for inputting request signals of a driver of the vehicle. The signal input device contains a sensor device which gradually senses a degree of activation of a driver-activated activation element between a position which represents non-activation and a position which represents maximum activation, and generates an activation signal which represents this degree of activation. The signal input device also contains evaluation electronics, into which the activation signal which is generated by the sensor device is input for the purpose of evaluation.
A signal input device in the form of a service brake valve for an electro-pneumatic service brake device as a vehicle device is known from International patent documents no. WO 2012/076514 A1.
In electro-pneumatic brake devices of modern utility vehicles there is generally a superordinate electro-pneumatic service brake circuit present which is assigned an electrical channel of the electro-pneumatic service brake valve or foot-operated brake module (FBM), i.e. when a service brake activation element (foot-operated brake pedal) of the service brake valve is activated, a sensor device generates an electrical activation signal as a function of the activation travel or activation angle corresponding to the braking request, which activation signal is input into evaluation electronics for signal conditioning. The conditioned activation signal is then input into a central electronic brake control unit in order to input a brake pressure, corresponding to the braking request into pneumatic service brake cylinders by corresponding activation of solenoid valves or pressure regulating modules.
In parallel with this, the activation of the foot-operated brake pedal of the service brake valve causes a plunger piston which is connected to the foot-operated brake pedal to activate, via a compression spring, a relay piston which in turn controls a double-seat valve of the service brake valve in order to generate a pneumatic control pressure, corresponding to the braking request. The pneumatic control pressure is applied to pneumatic channels of the service brake valve which form, via subordinate pneumatic service brake circuits, a brake pressure in the brake cylinders if the superordinate electrical service brake circuit has failed owing to a defect.
In the electro-pneumatic service brake valve or foot-operated brake module which is known, for example, from WO 2012/076514 A1 and is used to detect a service brake pedal position, a plunger which is operatively connected to the service brake pedal projects into a recess in the plunger piston which is connected to a spring plate which activates the relay piston by means of said compression spring. The foot-operated brake module contains a sensor device in the form of, for example, contactless travel measuring sensors with which the driver's service brake request and therefore the position of the foot-operated service brake pedal can be detected and evaluated in evaluation electronics. The sensor device or these evaluation electronics is/are not supplied with electrical energy when the vehicle ignition is switched off, and in this state can therefore not be used either for general detection of activation of the foot-operated service brake pedal or for detecting its degree of activation between a position which represents non-activation and a position which represents maximum activation.
In an electro-pneumatic service brake device described above with a superordinate electro-pneumatic service brake circuit and downstream pneumatic service brake circuits, legislators require that two brake circuits always respond if the driver activates the foot-operated service brake pedal. This must be the case even if a vehicle which is equipped with such a service brake device rolls downhill when the vehicle ignition is switched off.
In order, nevertheless, to ensure that the sensor device and the evaluation electronics are supplied with electrical energy when the vehicle ignition is switched off and the foot-operated service brake pedal is activated, in the foot-operated brake module known from WO 2012/076514 A1 an electronic circuit is proposed in combination with a microswitch which is activated by the relay piston. When the vehicle ignition is switched off, activation of the foot-operated service brake pedal is then detected and sensed via this microswitch and the electronic switch. A microswitch is understood here to be an electrical switch whose contacts are a distance of less than 3 mm from one another in the opened state. A known design is, for example, a microswitch with a snap-action system. Furthermore, designs as a normally-closed switch and a normally-open switch and as a changeover switch with the three contacts of a normally-closed contact, normally-open contact and switching tongue are also known. The switch state of the microswitch arises through contact with the relay piston in the foot-operated brake module. Through sufficient activation of the brake pedal, the relay piston is moved downward to such an extent that the microswitch changes its switch state.
The known foot-operated brake module therefore contains two independent sensing systems, specifically the travel measuring sensor or sensors with assigned evaluation electronics and the microswitch with assigned electronic circuit, wherein the microswitch merely activates or does not activate the states, and the travel measuring sensor can detect the degree of activation of the foot-operated service brake pedal.
However, such a microswitch always contains a mechanical contact. This contact is subject to certain mechanical stressing over the service life of the foot-operated brake module. This includes disadvantages such as, for example, wear of the microswitch mechanics, failure of the switching function as a result of external soiling, corrosion of the switching contacts of the microswitch, necessary sealing of the microswitch with respect to environmental influences (water, grease), freezing of the switching mechanics in the case of temperatures below zero and moisture, expenditure on mounting and formation of contacts for the microswitch and/or wear of the contact-forming element on the microswitch (contact pin).
In addition to the electro-pneumatic service brake device described above, in a modern vehicle there are further electrical, electro-pneumatic or electro-hydraulic vehicle devices, in which a signal input device is provided for inputting request signals of a driver of the vehicle with respect to the vehicle device, which signal input device contains a sensor device which gradually senses a degree of activation of an activation element, which can be activated by the driver, of the signal input device between a position which represents non-activation and a position which represents maximum activation, and generates an activation signal which represents this degree of activation, as well as evaluation electronics, into which the activation signal which is generated by the sensor device is input for the purpose of evaluation.
Such a vehicle device comprises, in particular, a parking brake device with a hand-operated or foot-operated device as a single input device as well as a foot pedal or a hand-operated activation element as an activation element, a clutch device with a clutch pedal-operated device as a signal input device and having a clutch foot pedal as an activation element or an accelerator pedal device having an accelerator pedal-operated device as a signal input device as well as having an accelerator foot pedal as an activation element.
The present invention is therefore based on the object of providing a vehicle device which has a higher level of availability or greater functionality with low additional expenditure.
Using the example of an electrical or electro-pneumatic service brake device as a vehicle device, the degree of activation of the foot-operated service brake pedal when the vehicle ignition is switched on is determined by the sensor device (e.g. contactless inductive travel measuring sensor), and transferred to a central brake control unit of the service brake device after evaluation by the evaluation electronics. This then results in the implementation of the deceleration requested by the driver in the brake actuators which are controlled electrically by the brake control unit.
In order to be able to sense activation of the foot-operated service brake pedal (gradually also in relation to the respective degree of activation) when the vehicle ignition is switched off, the invention provides that the sensor device and/or the evaluation electronics are designed to assume, in the switched-off state of the vehicle ignition system, a standby mode with reduced electrical energy consumption from an electrical energy source in comparison with an operating mode which prevails in the switched-on ignition. The energy consumption is not sufficient to ensure intended operation of the sensor device and/or of the evaluation electronics in the form of the sensing and evaluation of activation of the activation element, but to be moved in cycles into an energy-saving operating mode which ensures the intended operation of the sensor device and/or of the evaluation electronics in the form of the sensing and evaluation of activation of the activation element.
In other words, even in the switched-off state of the vehicle ignition system the sensor device and/or the evaluation electronics are not decoupled from an electrical energy supply but instead continue to be supplied thereby with electrical energy and additionally placed in a standby mode which is usually present with commercially available microprocessors for evaluation electronics, in which standby mode a significantly lower consumption of electrical energy prevails than in the operating mode which is present when the ignition is switched on.
However, in the standby mode which is present between the cyclic increased periods of consumption of electrical energy, the energy consumption is so low that intended operation of the sensor device and/or of the evaluation electronics in the form of the sensing and evaluation of activation of the activation element is not possible. Therefore, the energy consumption of the sensor device and/or of the evaluation electronics is increased in cycles and only during a relatively short time period within the scope of the energy-saving operating mode, in order to permit the intended operation of the sensor device and/or of the evaluation electronics in the form of the sensing and evaluation of activation of the activation element during such a time period.
Therefore, a changeover between the standby mode and the energy-saving operating mode of the sensor device and/or of the evaluation electronics takes place continuously within the scope of the cycle, and to be more precise at an interval from its period T. This cycle or the period of this cycle or the time period of the energy-saving operating mode is dimensioned here in such a way that activation of the activation element can be sensed in any case, even if there is a slight delay. The maximum delay of the sensing and evaluation of the signal is then just one time the period of a cycle. In other words, a type of pulsed sensing and evaluation of the signals of the sensor device is therefore implemented.
Compared to continuously occurring sensing and evaluation of the signals of the sensor device by the evaluation device in the operating mode when the vehicle ignition is switched on, these functions occur within the scope of the invention in a shorter period of time, and therefore more quickly, when the vehicle ignition is switched off, but given corresponding adaptation of the parameters which are decisive for the process this is sufficient to ensure reliable sensing and evaluation with sufficient accuracy.
Therefore, the invention makes use of an already existing sensor device/evaluation electronics combination with which, when the vehicle ignition is switched on, a degree of activation of the activation element is detected gradually, preferably for such a purpose also when the ignition is switched off, but with highly reduced consumption of electrical energy. Therefore, it is possible to dispense with a microswitch of the prior art as an additional sensing system.
Instead of sensing and evaluating the degree of activation of the activation element, it lies within the scope of the invention if during the energy-saving operating mode it was also merely sensed whether the activation element was generally activated or not (binary signal). This is also to be subsumed under intended operation.
If, in particular, the sensor device senses the degree of activation of the activation element in a contactless fashion, the disadvantages described at the beginning with respect to mechanical wear, environmental influences, assembly etc. are also eliminated.
The consumption of electrical energy in the energy-saving operating mode can be decreased compared to the consumption in the operating mode by a series of measures. For this purpose it is possible, in particular, to reduce the time period of the cyclically activated energy-saving operating mode to a time period which is just still sufficient to sense and evaluate activation of the activation element, but there is no restriction to this.
Furthermore, the evaluation electronics and/or the sensor device can be supplied by a device of the vehicle, e.g. by another electronic control device, which is supplied with current by the electrical energy source of the vehicle, with a voltage value, e.g. with 5 V, which is lower than the voltage value of e.g. 24 V which is supplied by the electrical energy source.
In particular, it is possible to use a voltage regulator or voltage transformer which supplies the sensor device and/or the evaluation electronics with a voltage value which is lower compared to a voltage value of the electrical energy source of the vehicle.
A preferred measure can also be to disconnect, from the electrical energy supply, circuit parts of the evaluation electronics which are not required, at least during the energy-saving operating mode.
Furthermore, energy-saving operating modes of a microcontroller of the evaluation electronics which are also already present can be used during the standby mode to reduce the energy consumption, for example by switching off peripherals, switching off the quartz, switching off the bus clock etc.).
As a result of the measures according to the invention, the actual energy consumption of electrical energy is obtained as an average value composed of very low electrical energy consumed during the cycles in the standby mode and of the relatively large amount of energy consumed during the pulse-like and brief cycles in the energy-saving operating mode, wherein this average value can be adapted by changing the ratio between the time period in the standby mode and the time period in the energy-saving operating mode. The level of consumed current during the energy-saving operating mode also plays a role here.
In the switched-off state of the vehicle ignition system and in the energy-saving operating mode, the electrical energy which is consumed by the sensor device and/or the evaluation electronics is particularly preferably lower than in the operating mode when the vehicle ignition system is in the switched-on state. This also contributes to a saving in electrical energy in the energy-saving operating mode, with the result that the risk of discharging of the on-board battery is reduced in the energy-saving operating mode.
Therefore, preferably three consumption levels of electrical energy are provided, wherein the lowest consumption level is in the standby mode when the vehicle ignition is switched off, the next highest consumption level is in the energy-saving operating mode, also when the vehicle ignition is switched off, and the highest consumption level is in the operating mode when the vehicle ignition is switched on.
According to one development, the sensor device senses the activation of a component which is directly or indirectly activated by the activation element, wherein the sensing with respect to this component is contactless or involves contacts, wherein contactless sensing is to be preferred for the reasons specified above.
In particular, a generator is provided which generates, in the cycles or cyclically, an event signal which causes the evaluation electronics and/or the sensor device to exit the standby mode and assume the energy-saving operating mode. In this context, the energy-saving operating mode is preferably assumed for a shorter time period t1 compared to the time period t0 in which the standby mode prevails, or for a time period t1 which is at least as long as the time period t0 of the standby mode.
When the vehicle ignition system is switched off and further electronic components of the vehicle device are in the standby mode, and therefore cannot trigger the cycle in which the sensor device and/or the vehicle evaluation electronics is/are adjusted cyclically from the standby mode into the energy-saving operating mode and back again, this cycle is therefore preferably triggered in an event-controlled fashion, for example by a counter signal or timer signal as an event signal of a generator. As a result, with the exception of the generator, the further electronics can “go to sleep” during the standby mode, with the result that in the standby mode additional electrical energy has to be made available only for the generator. The loading or discharging of the vehicle battery is reduced to a minimum in this way.
According to one development of these measures, the generator is integrated into the evaluation electronics. However, because the sensor sensing device of the vehicle device is in any case supplied continuously with electrical energy and the evaluation electronics are used, after sensing of activation of the activation element, to “wakeup” further electronic components of the vehicle device, i.e. to adjust them from the standby mode into the operating mode, it is advantageous to integrate the generator into the evaluation electronics of the sensor sensing device. However, as an alternative to this, the generator could also constitute a separate unit or else be integrated in another electronic component of the vehicle device.
Furthermore, the generator can be freely programmable with respect to a period T of the cycles of the event signal, the time period t1 during which the energy-saving operating mode is assumed, and/or the time period t0 during which the standby mode is assumed. In addition, the generator can be designed in such a way that it can be calibrated cyclically by a reference time measuring source.
According to one particularly preferred measure, the evaluation electronics communicates with at least one electronic open-loop or closed-loop control device of the vehicle system and is designed in such a way that when activation of the activation element in the energy-saving operating mode is sensed a wakeup signal is generated for the at least one electronic open-loop or closed-loop control device of the vehicle system, in order to place the device in its operating mode even when the ignition is switched off. Therefore, for example the entire vehicle device can then be employed for the intended use, e.g. for service braking operations and/or parking braking operations.
For this purpose, the evaluation electronics can communicate with the at least one electronic open-loop or closed-loop control device for the vehicle device by means of a data bus.
The evaluation electronics of the signal input device preferably have at least one microprocessor.
According to one development, the evaluation electronics of the signal input device have at least two microprocessors, only a first microprocessor of which is placed cyclically in the standby mode and in the energy-saving operating mode in the switched-off state of the vehicle ignition system, while in the switched-off state of the vehicle ignition system at least one further microcontroller of the evaluation electronics is completely deactivated and not placed in operation until when the ignition is switched on. Because just a single microprocessor of the at least two microprocessors is operated in the standby mode and also cyclically in the energy-saving operating mode, the energy consumption in these modes is low.
In this context, this first microcontroller of the evaluation electronics already has, from the time of manufacture, a standby mode in which the energy consumption is particularly low.
The vehicle device can be any vehicle device with the above features, in particular an electrical, electro-pneumatic or electro-hydraulic vehicle device having a signal input device for inputting request signals of a driver of the vehicle with respect to the vehicle device, which signal input device contains a sensor device which gradually senses a degree of activation of an activation element, which can be activated by the driver, of the signal input device between a position which represents non-activation and a position which represents maximum activation, and generates an activation signal which represents this degree of activation, as well as evaluation electronics, into which the activation signal which is generated by the sensor device is input for the purpose of evaluation.
In particular, the vehicle device is an electro-pneumatic or electrical service brake device of a vehicle having at least one electrical or electro-pneumatic service brake circuit, containing a service brake pedal device as a signal input device with a foot-operated service brake pedal as an activation element and at least one electrical channel which contains the sensor device and the evaluation electronics, wherein the sensor device directly or indirectly senses activation travel and/or an activation angle of the foot-operated service brake pedal.
Alternatively, the vehicle device can also be a parking brake device with a hand-operated or foot-operated device as a signal input device as well as a foot pedal or a hand-operated activation element as an activation element, a clutch device with a clutch pedal-operated device as a signal input device and having a clutch foot pedal as an activation element or an accelerator pedal device having an accelerator pedal-operated device as a signal input device as well as having an accelerator foot pedal as an activation element.
In summary, a (programmable) event signal of a generator is therefore used to exit the standby mode cyclically and assume the energy-saving operating mode. In addition, the sensing time of the sensor device is preferably shortened in the energy-saving operating mode. Furthermore, cyclical calibration of the event signal generator preferably takes place with respect to a more precise time source in order to correct fabrication-induced and/or ambient-temperature-induced deviations and/or a change in the ambient temperature.
It is advantageous overall that activation of the activation element can be sensed with only a short temporal delay by pulsed sensing of the sensor signal which is achieved using the measures above. The actual consumption of current is then obtained by forming mean values, i.e. averaging over the low consumption of current during the standby mode and a very brief and higher consumption of current compared thereto during the sensing time. By changing the period of the cycle, the average consumption of current can then be adapted to the electrical energy source which is respectively present in the vehicle.
The invention also relates to a vehicle having a vehicle device as described above.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.